A transmission is designed to transfer power from a prime mover to a machine for conducting work, such as, digging, trenching, excavating etc. The transmission may include one or more hydraulically actuated clutch assemblies. The clutches are positioned on a shaft that may include multiple passageways located within the clutch shaft. The passageways supply an actuating fluid to the clutches for engaging and disengaging the clutches. The clutches are actuated as per a gear selection made by a user or an electronic control module (ECM).
As the passageways are filled with the actuating fluid in a sequential or simultaneous manner, the actuating fluid drains from the passageways which are in the off state or are not pressurized. When the fluid drains from the passages air may become trapped inside clutch piston cavities or within the passageways in the shafts, or air pockets may be formed. Effectiveness of clutch fill time and gear shift quality can occur due to the entrapped air.
U.S. Patent Publication 2015/0198234 issued to Patenaude et al. and assigned to Caterpillar Inc. discloses an apparatus and method for alleviating air entrapped in a shaft of a power take off (PTO). In the disclosed reference a seal carrier has a number of cross ports that are connected to center passages. As the seal carrier rotates during operation, the seal carrier acts as a centrifuge and entrapped air in the hydraulic fluid is separated from the hydraulic fluid. The released air moves into the center passage and out through one of the connecting passages, ultimately to a tank or reservoir. While providing an effective arrangement to alleviate trapped air, there may be additional solutions. The present disclosure is directed to addressing one or more of the shortcomings as set forth above.